Studies are proposed aimed at confirming preliminary observations indicating that a new experimental model may have been found for the induction of respiratory distress syndrome in newborn rats. Female rats are fed from the first day of pregnancy a diet supplemented with N- Methyl Ethanolamine, a natural phospholipid base present only in trace amounts in mammalian tissues. Pregnancy and delivery proceed normally, but all the pups die within the first 24 hours. Preliminary histopathological observations have revealed the presence of some alterations in the lungs of the pups mimicking those seem in human infants with acute respiratory distress syndrome. Histopathologic studies will be carried out in order to characterize and better define the nature and significance of the observed pulmonary alterations. At the same time, biochemical studies will be initiated in order to probe the metabolic basis of the observed alterations, particular emphasis being placed on the biosynthesis and metabolism of lung surfactant.